Background
Emergence of pathogens and vectors in new hosts and new geographical areas poses great threats for public and veterinary health (Jones et al., 2008). Ticks are responsible for the spread of numerous pathogens worldwide and species belonging to the genus Hyalomma have been shown to have a particular epidemiologic role (Estrada-Peña, D́Amico, & Fernández-Ruiz, 2020; Hubálek, Sedláček, Estrada-Peña, Vojtíšek, & Rudolf, 2020). The tick species Hyalomma marginatum andHyalomma rufipes are the main vectors of Crimean-Congo haemorrhagic fever virus (CCHFV). This is a negative-sense single-stranded RNA virus belonging to the Nairoviridae family (order Bunyavirales) . It can cause debilitating human disease with no available casual treatment or vaccine and has a case fatality rate up to 30% (Bente et al., 2013). The public health significance of Crimean-Congo haemorrhagic fever is demonstrated by the fact that this infection is geographically the most widespread tick-transmitted viral disease in humans. It is found in the southern parts of Asia, the Middle East, Europe and Africa. The emergence of the virus is mainly determined by the distribution of Hyalomma ticks being responsible for the spread of the disease agent (Bente et al., 2013).
Hyalomma marginatum and Hy. rufipes are two-host ticks (Estrada-Peña, Mihalca, & Petney, 2018). The larva moults into a nymph on the same first host, feeding on that animal at both stages of development. For these two Hyalomma species, the first host is very often a bird. The fact that they do not change host before becoming a nymph greatly contributes to the successful geographical spread of these ticks, as it allows them to travel longer distances by attaching to the same migratory bird host. The adults moult from the engorged nymphs dropping off the first host and actively look for the second host, which is usually a large wild or domesticated mammal or human (Valcárcel et al., 2020; Walker et al., 2003).
Although the yearly arrival of immature Hyalomma ticks with migratory birds in temperate Europe has been a frequent phenomenon (Capek et al., 2014), the emergence of its adults has only been detected in higher numbers and wider distribution recently. Adults of Hy. marginatum were found in Slovakia (Nosek, Kožuch, & Lysý, 1982) and Austria (Duscher et al., 2018), Hyalomma rufipes adults were found in Hungary (S Hornok & Horváth, 2012). The adults of both tick species have recently been detected the Czech Republic (Hubálek et al., 2020; Lesiczka et al., 2022; Rudolf et al., 2021) Germany (Chitimia-Dobler et al., 2019), Sweden (Grandi et al., 2020), United Kingdom (Hansford et al., 2019; McGinley et al., 2021) and the Netherlands (Uiterwijk et al., 2021).
Citizen science, or community research, is a method that is gaining in popularity and involvement in many research fields today. The basic idea is that the data are collected or generated with the help of non-researchers but are analysed by researchers specializing in the given topic (Tran et al., 2021). Citizen science has many benefits, both for the researchers who evaluate the data and for the citizens who collect them. With the help of citizen science, for example, professionals have access to the data they need without having to pay for the work of hundreds of civilian researchers involved in the project, and the travel, accommodation and education that may be associated with it. It is also a great advantage that a project can be carried out over a large geographical area for many years (MacPhail & Colla, 2020). This approach has been successfully used in searching for the emergence of Hyalomma adults in several European countries (Grandi et al., 2020; Lesiczka et al., 2022; Uiterwijk et al., 2021).
In Hungary, we have limited published information about the occurrence of Hyalomma ticks. An engorged nymph of Hy. marginatum has been reported from a hedgehog (Erinaceus roumanicus ) living in a Budapest city park (G Földvári et al., 2011) and two larvae and a nymph were identified from robins (Erithacus rubecula ) (S Hornok et al., 2013) sampled to the south of the capital. Three Hy. rufipesnymphs were reported from a common whitethroat (Sylvia communis ) in another study (S. Hornok et al., 2016). The presence of antibodies against CCHFV has also been detected in Hungarian hares (Lepus europaeus ) (Németh et al., 2013), rodents (Földes et al., 2019) and recently also in humans (Magyar et al., 2021).
Based on these previous findings, the aim of our research was to obtain a comprehensive, nationwide picture of the occurrence of adultHyalomma ticks in Hungary through a citizen science approach. This kind of documentation is of great epidemiological importance because this is the first step for the prevention of emerging pathogens according to the DAMA (Document, Assess, Monitor, Act) protocol (Brooks et al., 2014). Based on this, we plan to continuously document the appearance of pathogens, their vectors and reservoirs hosts, then, after the appropriate scientific analyses (Assess), we will be able to identify the organisms that pose a threat to us and manage their targeted surveillance (Monitor). Thus, it will be possible to make adequate proposals to decision makers to take appropriate preventive measures (Act) (Brooks, Hoberg, & Boeger, 2019).